The subject matter disclosed herein relates to non-invasive imaging and, in particular, to dual-energy imaging.
In the fields of medical imaging and security screening, non-invasive imaging techniques have gained importance due to benefits that include unobtrusiveness, convenience, and speed. In medical and research contexts, non-invasive imaging techniques are used to image organs or tissues beneath the surface of the skin. Similarly, in industrial or quality control (QC) contexts, non-invasive imaging techniques are used to examine parts or items for hidden defects that may not be evident from an external examination. In security screening, non-invasive imaging techniques are typically used to examine the contents of containers (e.g., packages, bags, or luggage) without opening the containers and/or to screen individuals entering or leaving a secure location.
A number of non-invasive imaging modalities exist today. One such technique, dual-energy (DE) radiography, involves the acquisition of X-ray attenuation data at different energies within a relatively small time interval. The attenuation data at the different energy levels may then be used to decompose the imaged anatomy and create a first image of a first material (e.g., water or bone) and a second image of a second material (e.g., iodine, or other contrast agents). Because of the need to acquire sufficient attenuation data at multiple X-ray energies, the data or imaging sampling rate may be significantly increased (e.g., doubled) relative to scans where data is acquired at only a single energy. Such increased sampling rates may be difficult to obtain because of the physical, electrical, and/or mechanical constraints imposed by the imaging system hardware. Further, the smaller view times associated with the faster sampling rate may result in increased noise relative to the useful signal in such sampling schemes. Accordingly, techniques are needed to overcome the problems associated with dual energy image acquisition and reconstruction. The techniques described herein are intended to address one or more of these problems associated with dual energy imaging systems.